The proposed studies represent the continuation of a current project with the major aims of elucidation of metabolic pathways of sulfite and assessment of resulting toxicity. The areas of investigation include the dose dependency of S-sulfonate formation in the lung and aorta and separation and characterization of plasma protein S-sulfonates formed in vivo. The kinetics of the metabolic pathways of sulfite will be further investigated and the toxicological implications of the action of sulfite on enzymes, the fetus and the aorta and lung will be assessed.